internal ip schemes (was RE: [thelist] IIS5: subdomains, how to configure)

Steve Lewis slewis at macrovista.net
Thu Oct 31 21:08:01 CST 2002


Chris W. Parker wrote:

> 10.0.1.0. to my suprise this worked out fine. so now i have a different
> question. can i use any number from 0 to 255 in place of the x in
> 10.x.x.x ?

You cannot use an IP of 10.0.0.0 (address used to refer to the network,
not to a node/host) or 10.255.255.255 (aka the network broadcast
address) but otherwise yes, and Sean gives a very good reply to this
giving the complete set of non-routable IP ranges.  Just keep in mind
that you can never use the first or last address in your network (as
defined by your netmask).

> right?)? when would i need to change the subnet mask, if ever?
You may need to change the subnet mask when you are subdividing your
network, or expanding your network.  In those cases you would have to
know exactly what network topology you were attempting to create before
we could tell you what netmask to use.  The rules for subdividing
networks and calculating netmasks can be tricky, and it is easier to do
if you can do math in binary.

Technically, for the 10.0.0.0 class A network, the most permissive legal
netmask would be 255.0.0.0.  For the 172.16.0.0 class B network the most
permissive legal netmask would be 255.255.0.0.  For the 192.168.0 class
C network the most permissive legal netmask would be 255.255.255.0.

As a reminder, all hosts on a subnet should use the same netmask.

HTH

--Steve




More information about the thelist mailing list